// Unity C# reference source
// Copyright (c) Unity Technologies. For terms of use, see
// https://unity3d.com/legal/licenses/Unity_Reference_Only_License

using System;
using UnityEditor.SceneManagement;
using UnityEngine;
using Object = UnityEngine.Object;

namespace UnityEditor
{
    public sealed partial class EditorGUI
    {
        static private GUIContent s_SceneMismatch = EditorGUIUtility.TrTextContent("Scene mismatch (cross scene references not supported)");
        static private GUIContent s_TypeMismatch = EditorGUIUtility.TrTextContent("Type mismatch");
        static private GUIContent s_Select = EditorGUIUtility.TrTextContent("Select");

        [Flags]
        internal enum ObjectFieldValidatorOptions
        {
            None = 0,
            ExactObjectTypeValidation = (1 << 0)
        }

        internal delegate Object ObjectFieldValidator(Object[] references, System.Type objType, SerializedProperty property, ObjectFieldValidatorOptions options);

        // Takes object directly, no SerializedProperty.
        internal static Object DoObjectField(Rect position, Rect dropRect, int id, Object obj, Object objBeingEdited, System.Type objType, ObjectFieldValidator validator, bool allowSceneObjects, GUIStyle style = null)
        {
            return DoObjectField(position, dropRect, id, obj, objBeingEdited, objType, null, validator, allowSceneObjects, style != null ? style : EditorStyles.objectField);
        }

        // Takes SerializedProperty, no direct reference to object.
        internal static Object DoObjectField(Rect position, Rect dropRect, int id, System.Type objType, SerializedProperty property, ObjectFieldValidator validator, bool allowSceneObjects, GUIStyle style = null)
        {
            return DoObjectField(position, dropRect, id, null, null, objType, property, validator, allowSceneObjects, style != null ? style : EditorStyles.objectField);
        }

        internal enum ObjectFieldVisualType { IconAndText, LargePreview, MiniPreview }

        // when current event is mouse click, this function pings the object, or
        // if shift/control is pressed and object is a texture, pops up a large texture
        // preview window
        internal static void PingObjectOrShowPreviewOnClick(Object targetObject, Rect position)
        {
            if (targetObject == null)
                return;

            Event evt = Event.current;
            // ping object
            bool anyModifiersPressed = evt.shift || evt.control;
            if (!anyModifiersPressed)
            {
                EditorGUIUtility.PingObject(targetObject);
                return;
            }

            // show large object preview popup; right now only for textures
            if (targetObject is Texture)
            {
                PopupWindowWithoutFocus.Show(
                    new RectOffset(6, 3, 0, 3).Add(position),
                    new ObjectPreviewPopup(targetObject),
                    new[] { PopupLocation.Left, PopupLocation.Below, PopupLocation.Right });
            }
        }

        static Object AssignSelectedObject(SerializedProperty property, ObjectFieldValidator validator, System.Type objectType, Event evt)
        {
            Object[] references = { ObjectSelector.GetCurrentObject() };
            Object assigned = validator(references, objectType, property, ObjectFieldValidatorOptions.None);

            // Assign the value
            if (property != null)
                property.objectReferenceValue = assigned;

            GUI.changed = true;
            evt.Use();
            return assigned;
        }

        static private Rect GetButtonRect(ObjectFieldVisualType visualType, Rect position)
        {
            switch (visualType)
            {
                case ObjectFieldVisualType.IconAndText:
                case ObjectFieldVisualType.MiniPreview:
                    return new Rect(position.xMax - 19, position.y, 19, position.height);
                case ObjectFieldVisualType.LargePreview:
                    return new Rect(position.xMax - 36, position.yMax - 14, 36, 14);
                default:
                    throw new ArgumentOutOfRangeException();
            }
        }

        static bool HasValidScript(UnityEngine.Object obj)
        {
            MonoScript script = MonoScript.FromScriptedObject(obj);
            if (script == null)
            {
                return false;
            }
            Type type = script.GetClass();
            if (type == null)
            {
                return false;
            }
            return true;
        }

        static bool ValidDroppedObject(Object[] references, System.Type objType, out string errorString)
        {
            errorString = "";
            if (references == null || references.Length == 0)
            {
                return true;
            }

            var reference = references[0];
            Object obj = EditorUtility.InstanceIDToObject(reference.GetInstanceID());
            if (obj is MonoBehaviour || obj is ScriptableObject)
            {
                if (!HasValidScript(obj))
                {
                    errorString = $"Type cannot be found: {reference.GetType()}. Containing file and class name must match.";
                    return false;
                }
            }
            return true;
        }

        // Timeline package is using this internal overload so can't remove until that's fixed.
        internal static Object DoObjectField(Rect position, Rect dropRect, int id, Object obj, System.Type objType, SerializedProperty property, ObjectFieldValidator validator, bool allowSceneObjects, GUIStyle style)
        {
            return DoObjectField(position, dropRect, id, objType, property, validator, allowSceneObjects);
        }

        // This method takes either object reference directly, or via SerializedObject.
        // Since it's not easy to know which parameters are mutually exclusively used, this method is
        // private and internal/public methods instead EITHER take SerializedObject OR direct reference.
        static Object DoObjectField(Rect position, Rect dropRect, int id, Object obj, Object objBeingEdited, System.Type objType, SerializedProperty property, ObjectFieldValidator validator, bool allowSceneObjects, GUIStyle style)
        {
            if (validator == null)
                validator = ValidateObjectFieldAssignment;
            if (property != null)
                obj = property.objectReferenceValue;
            Event evt = Event.current;
            EventType eventType = evt.type;

            // special case test, so we continue to ping/select objects with the object field disabled
            if (!GUI.enabled && GUIClip.enabled && (Event.current.rawType == EventType.MouseDown))
                eventType = Event.current.rawType;

            bool hasThumbnail = EditorGUIUtility.HasObjectThumbnail(objType);

            // Determine visual type
            ObjectFieldVisualType visualType = ObjectFieldVisualType.IconAndText;
            if (hasThumbnail && position.height <= kObjectFieldMiniThumbnailHeight && position.width <= kObjectFieldMiniThumbnailWidth)
                visualType = ObjectFieldVisualType.MiniPreview;
            else if (hasThumbnail && position.height > kSingleLineHeight)
                visualType = ObjectFieldVisualType.LargePreview;

            Vector2 oldIconSize = EditorGUIUtility.GetIconSize();
            if (visualType == ObjectFieldVisualType.IconAndText)
                EditorGUIUtility.SetIconSize(new Vector2(12, 12));  // Have to be this small to fit inside a single line height ObjectField
            else if (visualType == ObjectFieldVisualType.LargePreview)
                EditorGUIUtility.SetIconSize(new Vector2(64, 64));

            switch (eventType)
            {
                case EventType.DragExited:
                    if (GUI.enabled)
                        HandleUtility.Repaint();

                    break;
                case EventType.DragUpdated:
                case EventType.DragPerform:

                    if (eventType == EventType.DragPerform)
                    {
                        string errorString;
                        if (!ValidDroppedObject(DragAndDrop.objectReferences, objType, out errorString))
                        {
                            Object reference = DragAndDrop.objectReferences[0];
                            EditorUtility.DisplayDialog("Can't assign script", errorString, "OK");
                            break;
                        }
                    }

                    if (dropRect.Contains(Event.current.mousePosition) && GUI.enabled)
                    {
                        Object[] references = DragAndDrop.objectReferences;
                        Object validatedObject = validator(references, objType, property, ObjectFieldValidatorOptions.None);

                        if (validatedObject != null)
                        {
                            // If scene objects are not allowed and object is a scene object then clear
                            if (!allowSceneObjects && !EditorUtility.IsPersistent(validatedObject))
                                validatedObject = null;
                        }

                        if (validatedObject != null)
                        {
                            DragAndDrop.visualMode = DragAndDropVisualMode.Generic;
                            if (eventType == EventType.DragPerform)
                            {
                                if (property != null)
                                    property.objectReferenceValue = validatedObject;
                                else
                                    obj = validatedObject;

                                GUI.changed = true;
                                DragAndDrop.AcceptDrag();
                                DragAndDrop.activeControlID = 0;
                            }
                            else
                            {
                                DragAndDrop.activeControlID = id;
                            }
                            Event.current.Use();
                        }
                    }
                    break;
                case EventType.MouseDown:
                    if (position.Contains(Event.current.mousePosition))
                    {
                        if (Event.current.button == 1)
                        {
                            var actualObject = property != null ? property.objectReferenceValue : obj;
                            var contextMenu = new GenericMenu();
                            contextMenu.AddItem(GUIContent.Temp("Properties..."), false, () => PropertyEditor.OpenPropertyEditor(actualObject));
                            contextMenu.DropDown(position);
                        }

                        if (Event.current.button != 0)
                            break;

                        // Get button rect for Object Selector
                        Rect buttonRect = GetButtonRect(visualType, position);

                        EditorGUIUtility.editingTextField = false;

                        if (buttonRect.Contains(Event.current.mousePosition))
                        {
                            if (GUI.enabled)
                            {
                                GUIUtility.keyboardControl = id;
                                if (property != null)
                                    ObjectSelector.get.Show(objType, property, allowSceneObjects);
                                else
                                    ObjectSelector.get.Show(obj, objType, objBeingEdited, allowSceneObjects);
                                ObjectSelector.get.objectSelectorID = id;

                                evt.Use();
                                GUIUtility.ExitGUI();
                            }
                        }
                        else
                        {
                            Object actualTargetObject = property != null ? property.objectReferenceValue : obj;
                            Component com = actualTargetObject as Component;
                            if (com)
                                actualTargetObject = com.gameObject;
                            if (showMixedValue)
                                actualTargetObject = null;

                            // One click shows where the referenced object is, or pops up a preview
                            if (Event.current.clickCount == 1)
                            {
                                GUIUtility.keyboardControl = id;

                                PingObjectOrShowPreviewOnClick(actualTargetObject, position);
                                evt.Use();
                            }
                            // Double click opens the asset in external app or changes selection to referenced object
                            else if (Event.current.clickCount == 2)
                            {
                                if (actualTargetObject)
                                {
                                    AssetDatabase.OpenAsset(actualTargetObject);
                                    GUIUtility.ExitGUI();
                                }
                                evt.Use();
                            }
                        }
                    }
                    break;
                case EventType.ExecuteCommand:
                    string commandName = evt.commandName;
                    if (commandName == ObjectSelector.ObjectSelectorUpdatedCommand && ObjectSelector.get.objectSelectorID == id && GUIUtility.keyboardControl == id && (property == null || !property.isScript))
                        return AssignSelectedObject(property, validator, objType, evt);
                    else if (commandName == ObjectSelector.ObjectSelectorClosedCommand && ObjectSelector.get.objectSelectorID == id && GUIUtility.keyboardControl == id && property != null && property.isScript)
                    {
                        if (ObjectSelector.get.GetInstanceID() == 0)
                        {
                            // User canceled object selection; don't apply
                            evt.Use();
                            break;
                        }
                        return AssignSelectedObject(property, validator, objType, evt);
                    }
                    break;
                case EventType.KeyDown:
                    if (GUIUtility.keyboardControl == id)
                    {
                        if (evt.keyCode == KeyCode.Backspace || (evt.keyCode == KeyCode.Delete && (evt.modifiers & EventModifiers.Shift) == 0))
                        {
                            if (property != null)
                                property.objectReferenceValue = null;
                            else
                                obj = null;

                            GUI.changed = true;
                            evt.Use();
                        }

                        // Apparently we have to check for the character being space instead of the keyCode,
                        // otherwise the Inspector will maximize upon pressing space.
                        if (evt.MainActionKeyForControl(id))
                        {
                            if (property != null)
                                ObjectSelector.get.Show(objType, property, allowSceneObjects);
                            else
                                ObjectSelector.get.Show(obj, objType, objBeingEdited, allowSceneObjects);
                            ObjectSelector.get.objectSelectorID = id;
                            evt.Use();
                            GUIUtility.ExitGUI();
                        }
                    }
                    break;
                case EventType.Repaint:
                    GUIContent temp;
                    if (showMixedValue)
                    {
                        temp = s_MixedValueContent;
                    }
                    else
                    {
                        // If obj or objType are both null, we have to rely on
                        // property.objectReferenceStringValue to display None/Missing and the
                        // correct type. But if not, EditorGUIUtility.ObjectContent is more reliable.
                        // It can take a more specific object type specified as argument into account,
                        // and it gets the icon at the same time.
                        if (obj == null && objType == null && property != null)
                        {
                            temp = EditorGUIUtility.TempContent(property.objectReferenceStringValue);
                        }
                        else
                        {
                            // In order for ObjectContext to be able to distinguish between None/Missing,
                            // we need to supply an instanceID. For some reason, getting the instanceID
                            // from property.objectReferenceValue is not reliable, so we have to
                            // explicitly check property.objectReferenceInstanceIDValue if a property exists.
                            if (property != null)
                                temp = EditorGUIUtility.ObjectContent(obj, objType, property.objectReferenceInstanceIDValue);
                            else
                                temp = EditorGUIUtility.ObjectContent(obj, objType);
                        }

                        if (property != null)
                        {
                            if (obj != null)
                            {
                                Object[] references = { obj };
                                if (EditorSceneManager.preventCrossSceneReferences && CheckForCrossSceneReferencing(obj, property.serializedObject.targetObject))
                                {
                                    if (!EditorApplication.isPlaying)
                                        temp = s_SceneMismatch;
                                    else
                                        temp.text = temp.text + string.Format(" ({0})", GetGameObjectFromObject(obj).scene.name);
                                }
                                else if (validator(references, objType, property, ObjectFieldValidatorOptions.ExactObjectTypeValidation) == null)
                                    temp = s_TypeMismatch;
                            }
                        }
                    }

                    switch (visualType)
                    {
                        case ObjectFieldVisualType.IconAndText:
                            BeginHandleMixedValueContentColor();
                            style.Draw(position, temp, id, DragAndDrop.activeControlID == id, position.Contains(Event.current.mousePosition));

                            Rect buttonRect = EditorStyles.objectFieldButton.margin.Remove(GetButtonRect(visualType, position));
                            EditorStyles.objectFieldButton.Draw(buttonRect, GUIContent.none, id, DragAndDrop.activeControlID == id, buttonRect.Contains(Event.current.mousePosition));
                            EndHandleMixedValueContentColor();
                            break;
                        case ObjectFieldVisualType.LargePreview:
                            DrawObjectFieldLargeThumb(position, id, obj, temp);
                            break;
                        case ObjectFieldVisualType.MiniPreview:
                            DrawObjectFieldMiniThumb(position, id, obj, temp);
                            break;
                        default:
                            throw new ArgumentOutOfRangeException();
                    }
                    break;
            }

            EditorGUIUtility.SetIconSize(oldIconSize);

            return obj;
        }

        private static void DrawObjectFieldLargeThumb(Rect position, int id, Object obj, GUIContent content)
        {
            GUIStyle thumbStyle = EditorStyles.objectFieldThumb;
            thumbStyle.Draw(position, GUIContent.none, id, DragAndDrop.activeControlID == id, position.Contains(Event.current.mousePosition));

            if (obj != null && !showMixedValue)
            {
                bool isCubemap = obj is Cubemap;
                bool isSprite = obj is Sprite;
                Rect thumbRect = thumbStyle.padding.Remove(position);

                if (isCubemap || isSprite)
                {
                    Texture2D t2d = AssetPreview.GetAssetPreview(obj);
                    if (t2d != null)
                    {
                        if (isSprite || t2d.alphaIsTransparency)
                            DrawTextureTransparent(thumbRect, t2d);
                        else
                            DrawPreviewTexture(thumbRect, t2d);
                    }
                    else
                    {
                        // Preview not loaded -> Draw icon
                        thumbRect.x += (thumbRect.width - content.image.width) / 2f;
                        thumbRect.y += (thumbRect.height - content.image.width) / 2f;
                        GUIStyle.none.Draw(thumbRect, content.image, false, false, false, false);

                        // Keep repaint until the object field has a proper preview
                        HandleUtility.Repaint();
                    }
                }
                else
                {
                    // Draw texture
                    Texture2D t2d = content.image as Texture2D;
                    if (t2d != null && t2d.alphaIsTransparency)
                        DrawTextureTransparent(thumbRect, t2d);
                    else
                        DrawPreviewTexture(thumbRect, content.image);
                }
            }
            else
            {
                GUIStyle s2 = thumbStyle.name + "Overlay";
                BeginHandleMixedValueContentColor();

                s2.Draw(position, content, id);
                EndHandleMixedValueContentColor();
            }
            GUIStyle s3 = thumbStyle.name + "Overlay2";
            s3.Draw(position, s_Select, id);
        }

        private static void DrawObjectFieldMiniThumb(Rect position, int id, Object obj, GUIContent content)
        {
            GUIStyle thumbStyle = EditorStyles.objectFieldMiniThumb;
            position.width = EditorGUI.kObjectFieldMiniThumbnailWidth;
            BeginHandleMixedValueContentColor();
            bool hover = obj != null; // we use hover texture for enhancing the border if we have a reference
            bool on =  DragAndDrop.activeControlID == id;
            bool keyFocus = GUIUtility.keyboardControl == id;
            thumbStyle.Draw(position, hover, false, on, keyFocus);
            EndHandleMixedValueContentColor();

            if (obj != null && !showMixedValue)
            {
                Rect thumbRect = new Rect(position.x + 1, position.y + 1, position.height - 2, position.height - 2); // subtract 1 px border
                Texture2D t2d = content.image as Texture2D;
                if (t2d != null && t2d.alphaIsTransparency)
                    DrawTextureTransparent(thumbRect, t2d);
                else
                    DrawPreviewTexture(thumbRect, content.image);

                // Tooltip
                if (thumbRect.Contains(Event.current.mousePosition))
                    GUI.Label(thumbRect, GUIContent.Temp(string.Empty, "Ctrl + Click to show preview"));
            }
        }

        internal static Object DoDropField(Rect position, int id, System.Type objType, ObjectFieldValidator validator, bool allowSceneObjects, GUIStyle style)
        {
            if (validator == null)
                validator = ValidateObjectFieldAssignment;
            Event evt = Event.current;
            EventType eventType = evt.type;

            // special case test, so we continue to ping/select objects with the object field disabled
            if (!GUI.enabled && GUIClip.enabled && (Event.current.rawType == EventType.MouseDown))
                eventType = Event.current.rawType;

            switch (eventType)
            {
                case EventType.DragExited:
                    if (GUI.enabled)
                        HandleUtility.Repaint();
                    break;
                case EventType.DragUpdated:
                case EventType.DragPerform:

                    if (position.Contains(Event.current.mousePosition) && GUI.enabled)
                    {
                        Object[] references = DragAndDrop.objectReferences;
                        Object validatedObject = validator(references, objType, null, ObjectFieldValidatorOptions.None);

                        if (validatedObject != null)
                        {
                            // If scene objects are not allowed and object is a scene object then clear
                            if (!allowSceneObjects && !EditorUtility.IsPersistent(validatedObject))
                                validatedObject = null;
                        }

                        if (validatedObject != null)
                        {
                            DragAndDrop.visualMode = DragAndDropVisualMode.Generic;
                            if (eventType == EventType.DragPerform)
                            {
                                GUI.changed = true;
                                DragAndDrop.AcceptDrag();
                                DragAndDrop.activeControlID = 0;
                                Event.current.Use();
                                return validatedObject;
                            }
                            else
                            {
                                DragAndDrop.activeControlID = id;
                                Event.current.Use();
                            }
                        }
                    }
                    break;
                case EventType.Repaint:
                    style.Draw(position, GUIContent.none, id, DragAndDrop.activeControlID == id);
                    break;
            }
            return null;
        }
    }

    internal class ObjectPreviewPopup : PopupWindowContent
    {
        readonly Editor m_Editor;
        readonly GUIContent m_ObjectName;
        const float kToolbarHeight = 22f;

        internal class Styles
        {
            public readonly GUIStyle toolbar = "preToolbar";
            public readonly GUIStyle toolbarText = "ToolbarBoldLabel";
            public GUIStyle background = "preBackground";
        }
        Styles s_Styles;

        public ObjectPreviewPopup(Object previewObject)
        {
            if (previewObject == null)
            {
                Debug.LogError("ObjectPreviewPopup: Check object is not null, before trying to show it!");
                return;
            }
            m_ObjectName = new GUIContent(previewObject.name, AssetDatabase.GetAssetPath(previewObject));   // Show path as tooltip on label
            m_Editor = Editor.CreateEditor(previewObject);
        }

        public override void OnClose()
        {
            if (m_Editor != null)
                Editor.DestroyImmediate(m_Editor);
        }

        public override void OnGUI(Rect rect)
        {
            if (m_Editor == null)
            {
                editorWindow.Close();
                return;
            }

            if (s_Styles == null)
                s_Styles = new Styles();

            // Toolbar
            GUILayout.BeginArea(new Rect(rect.x, rect.y, rect.width, kToolbarHeight), s_Styles.toolbar);
            EditorGUILayout.BeginHorizontal();
            GUILayout.FlexibleSpace();
            m_Editor.OnPreviewSettings();
            EditorGUILayout.EndHorizontal();
            GUILayout.EndArea();

            const float kMaxSettingsWidth = 240f;
            GUI.Label(new Rect(rect.x + 5f, rect.y, rect.width - kMaxSettingsWidth, kToolbarHeight), m_ObjectName, s_Styles.toolbarText);

            // Object preview
            Rect previewRect = new Rect(rect.x, rect.y + kToolbarHeight, rect.width, rect.height - kToolbarHeight);
            m_Editor.OnPreviewGUI(previewRect, s_Styles.background);
        }

        public override Vector2 GetWindowSize()
        {
            return new Vector2(400f, 300f + kToolbarHeight);
        }
    }
}
